The second suspect, Jagger Freeman, 25, was held at the 107 Precinct in Flushing and arraigned Sunday. He is charged with murder, robbery, assault and criminal possession of a weapon.
WATCH: Jagger Freeman being led out of the police precinct with fallen Detective Brian Simonsen's handcuffs:
Police believe Freeman acted as the lookout in the robbery.
Commissioner O'Neill said there is an internal review underway, and they are looking at the more than 40 gunshots that were fired by seven different officers that night.
Detective Simonsen, 42, was shot and killed by police bullets Tuesday at the scene of an armed robbery at the T-Mobile store in Richmond Hill, Queens.
Christopher Ransom, 27, of Brooklyn, now faces murder charges after Det. Simonsen, a 19-year veteran of the force, died from injuries suffered in the shooting.
NYPD Sergeant Matthew Gorman was also struck by gunfire but has since been treated and released.
Ransom was arraigned by video Friday from his hospital bed and pleaded not guilty.
A funeral for Simonsen is scheduled for Wednesday in Hampton Bays on Long Island, with viewings on Monday and Tuesday.
A prayer service and memorial was held Sunday at the 102nd Precinct.
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